FSA MegaExo BB-7100 Bottom Bracket – BSA, 24 mm, Di2
The FSA MegaExo BB-7100 is a threaded external-bearing bottom bracket for FSA 24 mm MegaExo cranks in English (BSA) frames, with a Di2-ready centre sleeve – a fresh BB-7100 brings back a quiet, smooth pedal stroke when the old one creaks, grinds or has play.
Why the FSA MegaExo BB-7100?
External bearings. The bearings sit outside the frame shell, so they can be larger and the spindle stiffer – for a direct, efficient feel. 
Accurate alloy cups. Die cast and CNC machined for a precise fit in the frame thread. 
Di2-ready centre sleeve. The adjustable composite sleeve leaves room for internally routed electronic shifting cables and keeps dirt and water away from the bearings. 
Several shell widths. With the included spacers it fits 68 mm and 73 mm BSA shells; the variable sleeve also covers 100 mm fat-bike shells. 
Sealed for all weather. Made for bikes that cover many kilometres in rain and dirt.
Signs your bottom bracket needs replacing
Clicking or creaking under load, especially when climbing. A crank that feels rough or gritty when you turn it by hand. Side-to-side play when you push the crank arms. A creaking, rough or loose bottom bracket costs energy and spoils every ride.
How it fits together
The BB-7100 is part 1. The BSA spacers come in the box; the wave spring washer (2) is not included – you find it separately in our shop.
1 – bottom bracket (two bearing cups threaded into the frame), 2 – wave spring washer, 3 – plastic spacer, 4 – left crank arm, 5 – crank bolt, 6 – drive-side crank arm with the 24 mm spindle, 7 – chainring or belt sprocket (direct mount).
Who is it for?
- Riders with an FSA MegaExo crank. Whose bottom bracket has started to creak, grind or show play.
- Belt-drive and gear-hub bikes. That cover many kilometres in rain and dirt and need a well-sealed bottom bracket.
- Bike builders. Fitting a 24 mm crank such as the FSA Comet to a BSA frame.
- Di2 bikes. That need room for the internal cable inside the shell.
Compatibility
| Standard | BSA / English thread (1.37" × 24 TPI) |
|---|---|
| Shell width | 68 / 73 mm (100 mm fat bike with the variable sleeve) |
| Spindle | 24 mm |
| Cranks | FSA MegaExo 24 mm cranks with a no-pinch-bolt left arm – Comet, Afterburner, V-Drive, Moto, Gravity |
| Cups | Aluminium, black; steel bearings |
| Centre sleeve | Adjustable composite, Di2-ready |
| In the box | Bottom bracket (2 bearing cups, centre sleeve), BSA spacers – no wave washer |
Fitting
- Clean and grease the frame threads. The drive-side cup has a left-hand thread on BSA frames.
- Use the spacers for your shell width as described in FSA's instructions.
- Tighten the cups with a suitable external bottom bracket tool to the torque given by FSA.
- Fit the crank, then the wave spring washer and the left arm, and check that there is no play.
Frequently asked questions
Does the FSA BB-7100 fit Shimano Hollowtech II cranks?
FSA designs the BB-7100 for FSA MegaExo 24 mm cranks with a no-pinch-bolt left arm. For other brands, check with us before ordering.
Does it fit a press-fit frame?
No. It is for threaded English (BSA) bottom bracket shells.
Is the wave spring washer included?
No. Order the FSA wave spring washer or the wave washer + spacer set separately.
We build and service belt-drive and gear-hub bikes every day in our Budapest workshop. Not sure which part you need? Send us a photo of your crank and bottom bracket and we will tell you what fits. FSA – Full Speed Ahead – has made bicycle components since 1993 and moved into cranksets and chainrings in 1995. FSA introduced the compact road crankset in 2004, and its MegaExo system with external bearings and a 24 mm spindle is one of the most widely used crank and bottom bracket platforms on mountain, gravel, trekking and urban bikes. FSA parts are fitted as original equipment by many bike brands, including our own Booda Bike belt-drive bikes.About FSA